void setup() {
    Serial.begin(115200);
}

//   0=>   0
//  47=> 100
//  94=> 200
// 141=> 300 (still following 47 * n)
// 192=> 400 (1 mark off)
// 246=> 500 (2 mark off)

static int MIN_METER = 0;
static int MAX_METER = 246;

void loop() {
    int value = Serial.parseInt();
    if(value != 0) {
        value = value;
        Serial.println(value);
        analogWrite(5, value);
    }
}